The present invention relates to an improved laser nozzle with an axially extending bore for the laser beam and the cutting gas and at least one auxiliary passage for the cutting gas disposed outwardly of the bore.
Laser nozzles are conventionally attached to a laser head and are fabricated in varied designs. Both the laser beam and the cutting gas flow through in an axial direction through the bore, and the gas is introduced at a suitable place through a channel in the laser head to flow into and thence through the bore with the laser beam. In this way, the laser beam and the cutting gas exit through the nozzle mouth and impinge upon the workpiece, which is usually underneath. Relative movement of the laser nozzle and workpiece causes a burn track to be produced in the workpiece as the metal is melted and oxidized. The cutting gas improves the burning process and at the same time "cleans" the burn track in the area of the point of burning produced by the laser beam.
Because the laser beam is narrowed or focused by a focusing device such as a lens, the passage in the laser head and the laser nozzle must be dimensioned and configured appropriately in the area of the focusing device. Thus, in the laser head the channel must have a certain minimum diameter for the focusing device, and the cross section of the channel or bore is thereafter reduced in the laser head and/or in the nozzle. This means that the longitudinal bore of the nozzle narrows at least once, and often several times, by reduced sections or by a continuous taper, or both, because the cross section of the bore is relatively narrow at the nozzle mouth.
It is also known to incorporate in such laser nozzles, auxiliary passages about the central bore for passage of some of the cutting gas through the nozzle to impinge upon the surface of the workpiece about the central bore.
It is an object of the present invention to provide a novel laser nozzle construction which is simple and inexpensive to fabricate and easy to change and which yields improved cutting results at high rates of feed of the workpiece relative to the laser cutting head.
It is also an object of the present invention to provide a laser head which increases the efficiency of the burning action provided by the cutting gas.
It is another object to provide an improved laser head construction utilizing such a novel laser nozzle so that the orientation of an auxiliary passage for the cutting gas can be optimized relative to the path of relative motion of the workpiece by the cutting head.